Sunday, November 29, 2009

How Come Greenland looks bigger on 2-d (ie. size of ausrailia) than on a 3-d globe (ie. 1/3 size of

This is a mind-boggling problem I have with 2-D maps. Also, I have noticed that Alaska is 1/2 as big as Austrailia on a 2-d map, and 1/3 that size on a globe. A complete and easy-to-understand answer would be appreciated. Thanks.



How Come Greenland looks bigger on 2-d (ie. size of ausrailia) than on a 3-d globe (ie. 1/3 size of AUS.)?replacement windows





The reason areas around the north pole on a map appear distorted and much bigger in size relative to areas closer to the equator is because, when transferring a map from a 3D object like the earth, they needed to be stretched in order to show them on a flat surface. No sphere can can be shown on a flat map without some kind of distortion. Greenland looks bigger because it is close to the north pole. The closer you get to the poles the more distortion occurs.



How Come Greenland looks bigger on 2-d (ie. size of ausrailia) than on a 3-d globe (ie. 1/3 size of AUS.)?windows mail internet explorer



Because the earth is a sphere and not flat. To portray it in 2 dimensions liberties are taken particularly at the poles.
It depends on map projection, i.e the way the globe is projected onto a 2D paper map.



You are probably thinking of the well known Mercator projection. In this projection the map scale expands in proportion to the secant of the latitude, so that Greenland is on a much larger scale than South Africa.



The Mercator projection has properties which are useful for navigation, such as conformality (meridians and parallels cross perpendicular) and a line of constant bearing (loxodrome) projects as a straight line. However these properties come at the expense of scale distortion.



There are other projections which preserve area scale, but which are not conformal, so no good for measuring bearings (e.g Mollweide projection)
See Rivet gun's answer, quite complete.

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